These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.59 s (backtrack: 0/20).

[ebuild   R    ] app-text/doxygen-1.16.1::gentoo  USE="-clang -debug -doc -dot -doxysearch -gui -test" LLVM_SLOT="22* -18 -19 -20 -21*" 8753 KiB

Total: 1 package (1 reinstall), Size of downloads: 8753 KiB